Intermediate System to Intermediate System (IS-IS) is a routing protocol utilized within an administrative domain of a wide area network, such routing protocols are referred to as interior gateway protocols. Each router in the network implementing IS-IS builds a database of the network topology by flooding link state information throughout the network. This database is referred to as the routing information base (RIB). The database determines routes and forwarding to reach destination Internet protocol IP addresses or IP address prefixes.
The neighbor discovery (ND) protocol is a link layer protocol used in connection with Internet protocol version 6 (IPv6) for discovery and auto-configuration of neighboring nodes on each link of a router. ND determines the Media Access Control (MAC) address for each neighboring node and other nodes in the network and can determine a mapping between these MAC addresses and IP addresses.
In some cases such as link flaps (momentary link outages or glitches) or link recovery IPv6 traffic drop can occur for the IPv6 routes computed by the IS-IS protocol, if the underlying MAC address is not resolved by the ND process. This traffic loss can diminish network efficiency and the loss of essential data that impacts the functioning of the source and destination of the traffic.